A **variable** is a container used to store data. You can say that a variable is a memory location where data is stored. Suppose there are students with different scores; their scores can be put in a variable. 

 

using System; 
public class HelloWorld
{
    static void Main()
    {
        string name = "Hello World";
        Console.WriteLine(name);
    }
}

At this point, the variable name has been declared. 
 We have a `name`, and we write it out and print it out. Take a look at another example:
 


using System;
public class HelloWorld
{
    static void Main()
    { 
     int Age = 20; 
     Console.WriteLine(Age);
    }
}

using System; 
public class HelloWorld
{
    static void Main()
    {
        int x = 50, z = 100;
        Console.WriteLine(x);
        Console.WriteLine(z);
    }
}

# Variable naming conventions
 * Variable names cannot start with numbers, reserved characters, or whitespaces -- they must start with alphabetic characters. 
 * Variable names must be unique and are always case sensitive. They can only contain letters, numbers, and underscore. 

  
  
 

We can declare a variable in the first line and then initialize by assigning a value in the following line. We will declare a variable first: 

using System;
public class HelloWorld
{
    static void Main()
    {
      int Age;
       Age = 36;
       Console.WriteLine(Age);
    }
}

# What is a constant variable? 
A **constant variable** is a variable whose value cannot be changed during program execution. In a constant variable, we cannot assign values at runtime; instead, it must be allocated at compile time.

class HelloWorld
{
    static void Main()
    {
     const int b = 20;
        System.Console.WriteLine(b);
    }
}

using System; 
public class HelloWorld
{
    static void Main()
    {
        char a = 'c';
        double temp = 10.68;
        bool b = false;
        string word = "Hello";
        Console.WriteLine(a);
        Console.WriteLine(temp);
        Console.WriteLine(b);
        Console.WriteLine(word);
        
    }
}

# ASP Data Types

There are two categories of data types: 
* reference 
* value type
 
 A **value type** is a data type that stores data within its memory allocation. A **reference type** is a data type that contains a pointer to another memory allocation that stores the data. 
 Value type variables are stored on the stack, and reference type variables are stored on the heap. 
 

What are ASP variables?

Variables are memory locations for storing data in ASP, with specific naming conventions. There are value and reference types, differing in how they handle memory.